Light emitting device
Summary by NHIP
Alternating Polarity Light Device
The device alternates voltage polarity between two electrodes while maintaining a fixed voltage on a central opposing electrode to prevent charge accumulation. Light emits from either the first or second organic compound layer depending on the applied polarity sequence.
Claim Score by NHIP
Abstract
A light emitting element, in which voltages having different polarities are applied alternately in order to prevent the accumulation of electric charge in an organic compound layer of the light emitting element, and in which light is always emitted, no matter whether a positive polarity voltage or a negative polarity voltage is applied, is provided. An opposing electrode is formed between a first electrode and a second electrode, and a first light emitting element having a compound layer that contains a first organic substance between the first electrode and the opposing electrode, and a second light emitting element having a compound layer that contains a second organic substance between the opposing electrode and the second electrode, are formed in the present invention. Note that a constant voltage (reference voltage) is imparted to the opposing electrode, and that voltages having inverse polarities are applied simultaneously, and alternately for fixed periods of time, to the first electrode and the second electrode. A light emitting element that always emits light, even if the polarity of the applied voltage changes, can thus be formed.
Term
Term ended
Expired 12 October 2023, 3 years ago.
- Priority
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25 claims: 5 independent, 20 dependent
- 1Broadest claimClaim Score 55, average(NHIP)A light emitting device comprising:a first electrode;a first chemical compound layer containing a first organic substance;an opposing electrode;a second chemical compound layer containing a second organic substance;and a second electrode, wherein the first chemical compound layer is disposed between the first electrode and the opposing electrode, and the second chemical compound layer is disposed between the opposing electrode and the second electrode;wherein a fixed voltage is applied to the opposing electrode;and wherein one of the first chemical compound layer and the second chemical compound layer emits light alternately for fixed periods by applying a voltage having one of a positive polarity and a negative polarity taking the fixed voltage as a reference alternately for the fixed periods to the first electrode and simultaneously applying a voltage which is inverse in polarity to the voltage applied to the first electrode taking the fixed voltage as a reference to the second electrode.
- 6A light emitting device comprising:a first electrode;a first chemical compound layer containing a first organic substance;an opposing electrode;a second chemical compound layer containing a second organic substance;and a second electrode, wherein the first chemical compound layer is disposed between the first electrode and the opposing electrode, and the second chemical compound layer is disposed between the opposing electrode and the second electrode;wherein a fixed voltage is applied to the opposing electrode;and wherein by applying a voltage having one of a positive polarity and a negative polarity taking the fixed voltage as a reference alternately for fixed periods to the first electrode and simultaneously applying a voltage which is inverse in polarity to the voltage applied to the first electrode taking the fixed voltage as a reference to the second electrode, a forward bias is applied to one of the first chemical compound layer and the second chemical compound layer, and simultaneously a reverse bias is applied to the other one of the first chemical compound layer and the second chemical compound layer;and polarities of the biases applied to the first chemical compound layer and the second chemical compound layer are changed alternately for the fixed periods.
- 11A light emitting device comprising:a first anode electrode;a first chemical compound layer containing a first organic substance;a cathode electrode;a second chemical compound layer containing a second organic substance;and a second anode electrode, wherein the first chemical compound layer is disposed between the first anode electrode and the cathode electrode, and the second chemical compound layer is disposed between the cathode electrode and the second anode electrode;wherein the first anode electrode and the second anode electrode are formed by an anodic material and the cathode electrode is formed by a cathodic material;wherein a fixed voltage is applied to the cathode electrode;and wherein the first chemical compound layer emits light by applying a voltage having a positive polarity taking the fixed voltage as a reference to the first anode electrode, and electric charge accumulated in the second chemical compound layer is simultaneously relieved by applying a voltage having a negative polarity taking the fixed voltage as a reference to the second anode electrode.
- 16A light emitting device comprising:a first electrode;a first chemical compound layer containing a first organic substance;an opposing electrode;a second chemical compound layer containing a second organic substance;and a second electrode, wherein the first chemical compound layer is disposed between the first electrode and the electrode, and the second chemical compound layer is disposed between the electrode and the second electrode;wherein the first electrode and the second electrode are formed by an anodic material and the opposing electrode is formed by a cathodic material;wherein a fixed voltage is applied to the opposing electrode;wherein by applying a voltage having one of the positive polarity and the negative polarity taking the voltage applied to the opposing electrode as a reference alternately for fixed periods to the first electrode, and simultaneously applying a voltage, which is inverse in polarity to the voltage applied to the first electrode taking the voltage applied to the opposing electrode as a reference, alternately for the fixed periods to the second electrode;the first chemical compound layer emits light during applying the positive polarity voltage to the first electrode;and the second chemical compound layer emits light during applying the positive polarity voltage to the second electrode.
- 21A light emitting device comprising:a first anode electrode;a first chemical compound layer containing a first organic substance;a cathode electrode;a second chemical compound layer containing a second organic substance;and a second anode electrode, wherein the first chemical compound layer is disposed between the first anode electrode and the cathode electrode, and the second chemical compound layer is disposed between the cathode electrode and the second anode electrode;wherein a fixed voltage is applied to the cathode electrode;wherein a voltage having one of a positive polarity and a negative polarity taking the fixed voltage as a reference is alternately for fixed periods applied to the first anode electrode and simultaneously a voltage which is inverse in polarity to the voltage applied to the first anode electrode taking the fixed voltage as a reference is applied to the second anode electrode, wherein the first chemical compound layer emits light by applying a voltage having the positive polarity taking the fixed voltage as a reference to the first anode electrode, and electric charge accumulated in the second chemical compound layer is simultaneously relieved by applying a voltage having the negative polarity taking the fixed voltage as a reference to the second anode electrode.
Independent claims5
163 paragraphs in 5 sections, as filed
BACKGROUND OF THE INVENTION
00011. Field of the Invention
0002The present invention relates to a light emitting element capable of being driven by alternating current drive, and to a light emitting device containing the light emitting element as a portion of the light emitting device.
00032. Description of the Related Art
0004A light emitting element is made from an anode, a cathode, and an organic compound layer sandwiched by the anode and the cathode. Light emission develops by carriers injected from both electrodes (electrons and holes) recombining within the organic compound layer and generating electrical excitation states.
0005However, electric charge accumulates in the organic compound layer in this type of light emitting element when using direct current drive, in which a fixed direction bias is always applied, and therefore there arises a problem in that the light emission lifetime and brightness are reduced.
0006Reports of using alternating current drive, in which a driver voltage applied to the light emitting element during light emission and a reverse bias that has an inverse polarity with respect to the driver voltage are applied alternately, are made as disclosed, for example, in JP 10-172760 A, JP 11-8064 A, and the like.
0007This is because the electric charge that accumulates in an inner portion of the organic compound layer is relieved by alternately applying voltages having different polarities to the organic compound layer by alternating current drive, and therefore reductions in the light emission lifetime and brightness can be suppressed.
0008However, in the case of light emitting elements in accordance with alternating current drive, the light emitting element normally has a laminate structure composed of an anode, an organic compound layer, and a cathode, and therefore light emission can be obtained only when a positive voltage is applied from the anode side and a negative voltage is applied to the cathode side, namely when a forward bias is applied. That is, the light emitting element does not emit light when a reverse bias is applied using alternating current drive.
0009Thus, when an effective light emitting time is reduced, display becomes dark. Therefore, when a high voltage is applied in order to maintain a predetermined brightness, there arises a problem in that degradation of the light emitting elements proceeds.
SUMMARY OF THE INVENTION
0010An object of the present invention is therefore to provide a light emitting element in which voltages having different polarities are alternately applied to an organic compound layer of the light emitting element in order to prevent the accumulation of electric charge, and in which light emission can always be obtained, whether a positive or a negative polarity voltage is applied.
0011In order to solve the aforementioned objective, an opposing electrode is formed between a first electrode and a second electrode in the present invention, and a first light emitting element is formed by forming a compound layer that contains a first organic substance between the first electrode and the opposing electrode. In addition, a second light emitting element is formed by forming a compound layer that contains a second organic substance between the opposing electrode and the second electrode.
0012Note that a fixed voltage (reference voltage) is always imparted to the opposing electrode formed here, and a voltage that has positive polarity with respect to the reference voltage and a voltage that has negative polarity with respect to the reference voltage are applied alternately to the first electrode. Further, a voltage that has positive polarity with respect to the reference voltage and a voltage that has negative polarity with respect to the reference voltage are applied alternately to the second electrode. It is characterized in that the polarity of the voltage applied to the first electrode and the polarity of the voltage applied to the second electrode are inverse in the present invention. Further, the first light emitting element and the second light emitting element share the opposing electrode in the present invention.
0013Note that the first electrode and the second electrode are formed in the present invention by using materials suitable for forming electrodes having identical polarities. Specifically, in the case where the first electrode and the second electrode are formed so as to become anodes, an anodic material having a high work function (preferably a material having a work function equal to or greater than 4.5 eV) is used in their formation. Conversely, in the case where the electrodes are formed so as to become cathodes, a cathodic material having a small work function (the work function is preferably equal to or less than 3.8 eV) is used in their formation. Note that, if the first electrode and the second electrode are formed by using an anodic material, then the opposing electrode is formed by using the opposite, i.e., a cathodic material. Further, if the first electrode and the second electrode are formed by using a cathodic material, then the opposing electrode is formed by using the opposite, i.e., an anodic material.
0014Note that, in the case where the first electrode and the second electrode are formed by using an anodic material and the common electrode is formed by using a cathodic material, a forward bias is applied to the compound layer that contains the first organic substance and structures the first light emitting element when a positive polarity voltage with respect to the reference voltage is applied to the first electrode. The carrier therefore recombines in an inner portion of the first organic compound layer, and then light is emitted. Further, a negative voltage with respect to the reference voltage is applied to the second electrode at this point as explained above, and a reverse bias is applied to the compound layer that contains the second organic substance and structures the second light emitting element. Then, the second light emitting element does not emit light. Note that, as a matter of convenience, light emission by the compound layer containing the first organic substance is expressed as the first light emitting element emitting light, and light emission by the compound layer that contains the second organic substance is expressed as the second light emitting element emitting light.
0015On the other hand, when a voltage having a negative polarity with respect to the reference voltage is applied to the first electrode, the compound layer that contains the first organic substance and structures the first light emitting element does not emit light because a reverse bias is applied to the first light emitting element. Further, a positive voltage with respect to the reference voltage is applied to the second electrode at this point, and a forward bias is applied to the compound layer that contains the second organic substance and structures the second light emitting element. Then, the second light emitting element emits light. Note that the accumulation of electric charge that develops within the compound layer containing the first organic substance when the forward bias is applied above can be relieved by applying the reverse bias here to the compound layer that contains the first organic substance.
0016The first light emitting element and the second light emitting element thus emit light alternately, and during a period when one light emitting element is emitting light, the other light emitting element does not emit light and accumulated electric charge can thus be relieved. Reductions in the light emission lifetime and degradation in brightness can therefore be suppressed. In addition, it becomes possible to perform display without shortening the effective light emission time because, even if voltages having different polarities are applied alternately, the light emitting element of the present invention is provided with light emitting elements showing light emission no matter what polarity voltage is applied. Thus, it is possible to solve problems in that the display becomes dark, and problems in that deterioration of the organic compound layers develops due to a high voltage being applied in order to maintain a predetermined brightness.
0017According to a structure of the present invention, there is provided a light emitting device including: <ul id="ul0001" list-style="none"><li id="ul0001-0001" num="0000"><ul id="ul0002" list-style="none"><li id="ul0002-0001" num="0018">a chemical compound layer containing a first electrode and a first organic substance;</li><li id="ul0002-0002" num="0019">an opposing electrode;</li><li id="ul0002-0003" num="0020">a chemical compound layer containing a second organic substance; and</li><li id="ul0002-0004" num="0021">a second electrode;</li></ul></li></ul>
0022in which: <ul id="ul0003" list-style="none"><li id="ul0003-0001" num="0000"><ul id="ul0004" list-style="none"><li id="ul0004-0001" num="0023">the chemical compound layer containing the first organic compound is disposed between the first electrode and the opposing electrode;</li><li id="ul0004-0002" num="0024">the chemical compound layer containing the second organic substance is disposed between the opposing electrode and the second electrode;</li><li id="ul0004-0003" num="0025">a fixed voltage is applied to the opposing electrode; and</li><li id="ul0004-0004" num="0026">by applying a voltage having one of the positive polarity and the negative polarity to the first electrode, taking the voltage applied to the opposing electrode as a reference, and simultaneously applying a voltage, to the second electrode, which is inverse in polarity to the voltage applied to the first electrode: <ul id="ul0005" list-style="none"><li id="ul0005-0001" num="0027">one of the chemical compound layer containing the first organic substance or the chemical compound layer containing the second organic substance emits light.</li></ul></li></ul></li></ul>
0028According to a structure of the present invention, there is provided a light emitting device including: <ul id="ul0006" list-style="none"><li id="ul0006-0001" num="0000"><ul id="ul0007" list-style="none"><li id="ul0007-0001" num="0029">a chemical compound layer containing a first electrode and a first organic substance;</li><li id="ul0007-0002" num="0030">an opposing electrode;</li><li id="ul0007-0003" num="0031">a chemical compound layer containing a second organic substance; and</li><li id="ul0007-0004" num="0032">a second electrode;</li></ul></li></ul>
0033in which: <ul id="ul0008" list-style="none"><li id="ul0008-0001" num="0000"><ul id="ul0009" list-style="none"><li id="ul0009-0001" num="0034">the chemical compound layer containing the first organic substance is disposed between the first electrode and the opposing electrode;</li><li id="ul0009-0002" num="0035">the chemical compound layer containing the second organic substance is disposed between the opposing electrode and the second electrode;</li><li id="ul0009-0003" num="0036">a fixed voltage is applied to the opposing electrode; and</li><li id="ul0009-0004" num="0037">by applying a voltage having one of the positive polarity and the negative polarity alternately for fixed periods to the first electrode, taking the voltage applied to the opposing electrode as a reference, and simultaneously applying a voltage, alternately for fixed periods, to the second electrode, which is inverse in polarity to the voltage applied to the first electrode: <ul id="ul0010" list-style="none"><li id="ul0010-0001" num="0038">one of the chemical compound layer containing the first organic substance and the chemical compound layer containing the second organic substance emits light alternately for fixed periods.</li></ul></li></ul></li></ul>
0039According to a structure of the present invention, there is provided a light emitting device including: <ul id="ul0011" list-style="none"><li id="ul0011-0001" num="0000"><ul id="ul0012" list-style="none"><li id="ul0012-0001" num="0040">a chemical compound layer containing a first electrode and a first organic substance;</li><li id="ul0012-0002" num="0041">an opposing electrode;</li><li id="ul0012-0003" num="0042">a chemical compound layer containing a second organic substance; and</li><li id="ul0012-0004" num="0043">a second electrode;</li></ul></li></ul>
0044in which: <ul id="ul0013" list-style="none"><li id="ul0013-0001" num="0000"><ul id="ul0014" list-style="none"><li id="ul0014-0001" num="0045">the chemical compound layer containing the first organic substance is disposed between the first electrode and the opposing electrode;</li><li id="ul0014-0002" num="0046">the chemical compound layer containing the second organic substance is disposed between the opposing electrode and the second electrode;</li><li id="ul0014-0003" num="0047">a fixed voltage is applied to the opposing electrode; and</li><li id="ul0014-0004" num="0048">by applying voltages having one of the positive polarity and the negative polarity alternately to the first electrode for fixed periods, taking the voltage applied to the opposing electrode as a reference, and by simultaneously applying voltages, which are inverse in polarity to the voltages applied to the first electrode, alternately to the second electrode for fixed periods: <ul id="ul0015" list-style="none"><li id="ul0015-0001" num="0049">a forward bias is applied to one of the chemical compound layer containing the first organic substance or the chemical compound layer containing the second organic substance;</li><li id="ul0015-0002" num="0050">simultaneously a reverse bias is applied to the other chemical compound layer; and</li><li id="ul0015-0003" num="0051">the polarities of the biases applied to the chemical compound layer containing the first organic substance and the chemical compound layer containing the second organic substance are changed alternately for fixed periods.</li></ul></li></ul></li></ul>
0052In a structure of the present invention, there is provided a light emitting device including: <ul id="ul0016" list-style="none"><li id="ul0016-0001" num="0000"><ul id="ul0017" list-style="none"><li id="ul0017-0001" num="0053">a chemical compound layer containing a first electrode and a first organic substance;</li><li id="ul0017-0002" num="0054">an opposing electrode;</li><li id="ul0017-0003" num="0055">a chemical compound layer containing a second organic substance; and</li><li id="ul0017-0004" num="0056">a second electrode;</li></ul></li></ul>
0057wherein: <ul id="ul0018" list-style="none"><li id="ul0018-0001" num="0000"><ul id="ul0019" list-style="none"><li id="ul0019-0001" num="0058">the chemical compound layer containing the first organic substance is disposed between the first electrode and the opposing electrode;</li><li id="ul0019-0002" num="0059">the chemical compound layer containing the second organic substance is disposed between the opposing electrode and the second electrode;</li><li id="ul0019-0003" num="0060">the first electrode and the second electrode are formed by an anodic material;</li><li id="ul0019-0004" num="0061">the opposing electrode is formed by a cathodic material;</li><li id="ul0019-0005" num="0062">a fixed voltage is applied to the opposing electrode; and</li><li id="ul0019-0006" num="0063">by applying a voltage having a positive polarity to the first electrode, taking the voltage applied to the opposing electrode as a reference, and simultaneously applying a voltage having a negative polarity to the second electrode, taking the voltage applied to the opposing electrode as a reference: <ul id="ul0020" list-style="none"><li id="ul0020-0001" num="0064">the chemical compound layer containing the first organic substance emits light; and</li><li id="ul0020-0002" num="0065">electric charge that accumulates in the chemical compound layer containing the second organic substance is simultaneously relieved.</li></ul></li></ul></li></ul>
0066In a structure of the present invention, there is provided a light emitting device including: <ul id="ul0021" list-style="none"><li id="ul0021-0001" num="0000"><ul id="ul0022" list-style="none"><li id="ul0022-0001" num="0067">a chemical compound layer containing a first electrode and a first organic substance;</li><li id="ul0022-0002" num="0068">an opposing electrode;</li><li id="ul0022-0003" num="0069">a chemical compound layer containing a second organic substance; and</li><li id="ul0022-0004" num="0070">a second electrode;</li></ul></li></ul>
0071in which: <ul id="ul0023" list-style="none"><li id="ul0023-0001" num="0000"><ul id="ul0024" list-style="none"><li id="ul0024-0001" num="0072">the chemical compound layer containing the first organic substance is disposed between the first electrode and the opposing electrode;</li><li id="ul0024-0002" num="0073">the chemical compound layer containing the second organic substance is disposed between the opposing electrode and the second electrode;</li><li id="ul0024-0003" num="0074">the first electrode and the second electrode are formed by an anodic material;</li><li id="ul0024-0004" num="0075">the opposing electrode is formed by a cathodic material;</li><li id="ul0024-0005" num="0076">a fixed voltage is applied to the opposing electrode;</li><li id="ul0024-0006" num="0077">voltages having one of the positive polarity and the negative polarity are applied alternately to the first electrode for fixed periods, taking the voltage applied to the opposing electrode as a reference, and voltages, which are inverse in polarity to the voltages applied to the first electrode, are simultaneously applied alternately to the second electrode for fixed periods;</li><li id="ul0024-0007" num="0078">the chemical compound layer containing the first organic substance emits light by the positive polarity voltages being applied to the first electrode; and</li><li id="ul0024-0008" num="0079">the chemical compound layer containing the second organic substance emits light by the positive polarity voltages being applied to the second electrode.</li></ul></li></ul>
0080According to a structure of the present invention, there is provided a light emitting device including: <ul id="ul0025" list-style="none"><li id="ul0025-0001" num="0000"><ul id="ul0026" list-style="none"><li id="ul0026-0001" num="0081">a chemical compound layer containing a first electrode and a first organic substance;</li><li id="ul0026-0002" num="0082">an opposing electrode;</li><li id="ul0026-0003" num="0083">a chemical compound layer containing a second organic substance; and</li><li id="ul0026-0004" num="0084">a second electrode;</li></ul></li></ul>
0085in which: <ul id="ul0027" list-style="none"><li id="ul0027-0001" num="0000"><ul id="ul0028" list-style="none"><li id="ul0028-0001" num="0086">the chemical compound layer containing the first organic substance is disposed between the first electrode and the opposing electrode;</li><li id="ul0028-0002" num="0087">the chemical compound layer containing the second organic substance is disposed between the opposing electrode and the second electrode;</li><li id="ul0028-0003" num="0088">the first electrode and the second electrode are formed by an anodic material;</li><li id="ul0028-0004" num="0089">the opposing electrode is formed by a cathodic material;</li><li id="ul0028-0005" num="0090">a fixed voltage is applied to the opposing electrode;</li><li id="ul0028-0006" num="0091">voltages having one of the positive polarity and the negative polarity are applied alternately to the first electrode for fixed periods, taking the voltage applied to the opposing electrode as a reference, and voltages, which are inverse in polarity to the voltages applied to the first electrode, are simultaneously applied alternately to the second electrode for fixed periods;</li><li id="ul0028-0007" num="0092">the chemical compound layer containing the first organic substance emits light by the positive polarity voltages being applied to the first electrode; and</li><li id="ul0028-0008" num="0093">electric charge that accumulates in the chemical compound layer containing the second organic substance is simultaneously relieved.</li></ul></li></ul>
0094The opposing electrode in each of the aforementioned structures is formed by using a light transmitting conductive material. Note that, in the case where light generated by the compound layer containing the organic substance and is emitted from only any one of the first electrode and the second electrode of the present invention, the electrode on the side to which the light is emitted is formed by using a light transmitting material, and the electrode on the side that shields light is formed by using a light blocking material. Note that light generated in the compound layer that contains the organic substance can be efficiently emitted by using a material having, specifically, a transmittivity which is equal to or greater than 40% with respect to visible light as the light transmitting material. Further, the light generated in the compound layer that contains the organic substance can be sufficiently blocked by using a material having, specifically, a transmittivity in visible light which is less than 10% as the light blocking material.
BRIEF DESCRIPTION OF THE DRAWINGS
0095In the accompanying drawings:
0096<figref idref="DRAWINGS">FIGS. 1A and 1B</figref> are diagrams for explaining an element structure of a light emitting element of the present invention;
0097<figref idref="DRAWINGS">FIG. 2</figref> is a diagram for explaining a voltage applied to the light emitting element of the present invention;
0098<figref idref="DRAWINGS">FIGS. 3A and 3B</figref> are diagrams for explaining a bottom emission type light emitting element;
0099<figref idref="DRAWINGS">FIGS. 4A and 4B</figref> are diagrams for explaining a top emission type light emitting element;
0100<figref idref="DRAWINGS">FIGS. 5A and 5B</figref> are diagrams for explaining about a passive matrix light emitting device;
0101<figref idref="DRAWINGS">FIG. 6</figref> is a diagram for explaining about an active matrix light emitting device;
0102<figref idref="DRAWINGS">FIGS. 7A and 7B</figref> are diagrams for explaining about an active matrix light emitting device;
0103<figref idref="DRAWINGS">FIGS. 8A to 8D</figref> are diagrams for explaining about an active matrix light emitting device;
0104<figref idref="DRAWINGS">FIG. 9</figref> is a diagram for explaining about a passive matrix light emitting device; and
0105<figref idref="DRAWINGS">FIGS. 10A to 10H</figref> are diagrams for explaining about electric equipments.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Embodiment Mode
0106An embodiment mode of the present invention is explained using <figref idref="DRAWINGS">FIGS. 1A and 1B</figref>. Note that <figref idref="DRAWINGS">FIGS. 1A and 1B</figref> are diagrams that show an element structure of a light emitting element in the present invention.
0107A first electrode <b>102</b> is formed on a substrate <b>101</b> in <figref idref="DRAWINGS">FIGS. 1A and 1B</figref>. Note that the first electrode <b>102</b> is electrically connected to a first electric power source <b>109</b>, which is an alternating current power source, and voltages having either positive or negative polarity with respect to a reference voltage are applied alternately from the first electric power source <b>109</b>, as shown in <figref idref="DRAWINGS">FIG. 2</figref>. Further, the first electrode <b>102</b> is formed by using a material having a large work function that is capable of forming an anode (anodic material) in the embodiment mode of the present invention. Note that it is preferable the formation be performed by using a material having a work function which is equal to or greater than 4.5 eV as the anodic material. Specifically, an indium tin oxide (ITO), which is known as a light transmitting conductive film, indium zinc oxide (IZO) in which 2 to 20% of zinc oxide (ZnO) is mixed into indium oxide, and in addition, element residing in groups 4 to 11 of the long-period type periodic table, such as gold (Au), platinum (Pt), nickel (Ni), tungsten (W), chromium (Cr), molybdenum (Mo), iron (Fe), cobalt (Co), copper (Cu), palladium (Pd) and the like, and chemical compounds of these elements can be used. Further, in the case where the first electrode <b>102</b> functions as an electrode for emitting light that is generated in a first organic compound layer <b>105</b> or a second organic compound layer <b>106</b> to the outside, the first electrode <b>102</b> is formed using a light transmitting material having a transmittivity to such an extent that can emit light from the first electrode <b>102</b> (specifically, the transmittivity of visible light is equal to or greater than 40%). Conversely, in the case where a structure that emits light only from a second electrode <b>103</b> side is formed, the first electrode <b>102</b> is formed using a light blocking material having a transmittivity to such an extent that can block the emission of light from the first electrode <b>102</b> (specifically, the transmittivity of visible light is less than 10%).
0108Next, the first organic compound layer <b>105</b> is formed on the first electrode <b>102</b>. Note that low molecular weight organic compound materials and high molecular weight organic compound materials can be used as materials for forming the first organic compound layer <b>105</b>. Further, the term organic compound material includes not only those materials made from only known organic compound materials, but also organic compound materials that contain inorganic compounds in a portion therein. Note that, although a compound layer that contains a first organic substance is denoted by the term first organic compound layer, and a compound layer that contains a second organic substance is denoted by the term second organic compound layer, as a matter of convenience in this embodiment mode and embodiments shown hereafter, they each denote the same things and may be formed by using the aforementioned materials.
0109Note that the organic compound layer <b>105</b> is formed by a laminate that uses a functional materials such as a hole transporting material, a light emitting material, an electron transporting material, a blocking material, and in addition, a hole injecting material and the like. Furthermore, the laminate structure of the organic compound layer may be combined freely in the present invention. Several examples of suitable materials are given below. However, the materials used in the present invention are not limited to these. In addition, the present invention is not limited to the examples of functional materials provided above, and other known functional materials can also be used.
0110Aromatic amine-based compounds (namely, those having benzene ring-nitrogen bonds) are suitable for the hole transporting material. Materials widely used include:, starburst type aromatic amine compounds such as 4,4′-bis[N-(1-naphthyl)-N-phenyl-amino]-biphenyl which is the derivative (hereinafter, referred to as α-NPD); 4,4′,4″-tris(N,N-diphenyl-amino)-triphenylamine (hereinafter, referred to as TDATA); and 4,4′,4″-tris[N-(3-methylphenyl)-N-phenyl-amino]-triphenylamine (hereinafter, referred to as MTDATA) in addition to the above-mentioned TPD thereof.
0111Specifically, effective as the light emitting material are various fluorescent pigments as well as metal complexes such as tris(8-quinolinolato)aluminum (hereinafter, referred to as Alq<sub>3</sub>), tris(4-methyl-8-quinolinolato)aluminum (hereinafter, referred to as Almq<sub>3</sub>), bis(10-hydroxybenzo[h]quinolinato)beryllium (hereinafter, referred to as BeBq<sub>2</sub>), bis(2-methyl-8-quinolinolate)-(4-hydroxy-biphenylyl)aluminum (hereinafter, referred to as BAlq), bis[2-(2-hydroxyphenyl)-benzoxazolato]zinc (hereinafter, referred to as Zn(BOX)<sub>2</sub>), and bis[2-(2-hydroxyphenyl)-benzothiazolato]zinc (hereinafter, referred to as Zn(BTZ)<sub>2</sub>). In addition, triplet light emission materials may also be used, and metal complexes each containing platinum or iridium as a central metal can also be used. The triplet light emission materials include: tris(2-phenylpyridine)iridium (hereinafter, referred to as Ir(ppy)<sub>3</sub>); 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrin-platinum (hereinafter, referred to as PtOEP); and the like.
0112Metal complexes having quinoline skeleton or benzoquinoline skeleton such as the above-mentioned Alq<sub>3</sub>, Almq<sub>3</sub>, and BeBq<sub>2</sub>, BAlq serving as a mixed ligand complex, and the like are suitable for electron transporting materials. Metal complexes having oxazole-based ligands or thiazole-based ligands such as Zn(BOX)<sub>2 </sub>and Zn(BTZ)<sub>2 </sub>are also suitable. Furthermore, other than metal complexes, oxadiazole derivatives such as 2-(4-biphenylyl)-5-(4-tert-buthylphenyl)-1,3,4-oxadiazole (hereinafter, referred to as PBD) and 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazole-2-yl]benzene (hereinafter, referred to as OXD-7), triazole derivatives such as 3-(4-tert-butylphenyl)-4-phenyl-5-(4-biphenylyl)-1,2,4-triazole (hereinafter, referred to as TAZ) and 3-(4-tert-butylphenyl)-4-(4-ethylphenyl)-5-(4-biphenylyl)-1,2,4-triazole (hereinafter, referred to as p-EtTAZ), and phenanthroline derivatives such as bathophenanthroline (hereinafter, referred to as Bphen) and bathocuproine (hereinafter, referred to as BCP) can be used therefor.
0113Furthermore, within the framework of organic compounds, porphyrin-based compounds are effective for the hole injection material, so that a phthalocyanine (hereinafter, referred to as H<sub>2</sub>-Pc), a copper phthalocyanine (hereinafter, referred to as CuPc), or the like can be used therefor. In addition, materials obtained by performing chemical doping on conductive polymeric compounds are also effective therefor, so that polyethylene dioxythiophene (hereinafter, referred to as PEDOT) doped with polystyrene sulfonate (hereinafter, referred to as PSS), polyaniline, polyvinylcarbazole (hereinafter, referred to as PVK), or the like can be used therefor.
0114Furthermore, the above-mentioned BAlq, OXD-7, TAZ, p-EtTAZ, Bphen, BCP, or the like can be used for the blocking material.
0115An opposing electrode <b>104</b> is formed next on the first organic compound layer <b>105</b>. Note that the opposing electrode <b>104</b> is formed by using a material having a small work function and capable of forming a cathode (cathodic material), in the embodiment mode of the present invention. Note that it is preferable to use materials having a work function which is equal to or less than 3.8 eV as the cathodic material here for the formation. Elements residing in group 1 or group 2 of the element periodic law, that is, alkaline metals such as Li and Cs, and alkaline earth metals such as Mg, Ca and Sr, alloys and chemical compounds that contain these elements, and in addition, transition metals containing rare earth metals can be used in forming the opposing electrode. A laminate with a metal such as Al, Ag, or ITO (including alloys) may also be formed.
0116Further, the opposing electrode <b>104</b> forms a first light emitting element <b>107</b> using the first electrode <b>102</b> and the first organic compound layer <b>105</b>, as explained above. Further, a third electric power source <b>111</b> is electrically connected to the opposing electrode <b>104</b>, and a fixed voltage (reference voltage) is imparted from the third electric power source <b>111</b> to the opposing electrode <b>104</b> as shown in <figref idref="DRAWINGS">FIG. 2</figref>. In addition, the opposing electrode <b>104</b> also functions as one electrode that forms a second light emitting element <b>108</b> as explained below. The opposing electrode <b>104</b> is therefore formed by using a light transmitting conductive material so as to be able to transmit light whether the first light emitting element <b>107</b> or the second light emitting element <b>108</b> emits light.
0117A second organic compound layer <b>106</b> is formed next on the opposing electrode <b>104</b>. Note that the second organic compound layer <b>106</b> can be formed by using the known organic compound materials shown when the first organic compound layer <b>105</b> is formed. It is preferable to form the second organic compound layer <b>106</b> by using the same material as that used for the first organic compound layer <b>105</b>. Further, in the case where the first organic compound layer <b>105</b> and the second organic compound layer <b>106</b> have laminate structures composed of a plurality of organic compound materials, it is also preferable to form them so that their order of lamination with respect to the electrodes (anode or cathode), their film thicknesses, and the like are also the same.
0118The second electrode <b>103</b> is formed on the second organic compound layer <b>106</b>. Note that the second electrode <b>103</b> is electrically connected to a second electric power source <b>110</b>, which is an alternating current power source, and voltages having positive or negative polarity with respect to the reference voltage are alternately applied from the second electric power source <b>110</b> as shown in <figref idref="DRAWINGS">FIG. 2</figref>. Further, the voltage applied to the second electrode <b>103</b> here is a voltage having the inverse polarity and it is applied at the same timing as that of the voltage applied to the first electrode <b>102</b> explained above. Furthermore, in the embodiment mode of the present invention, the second electrode <b>103</b> is formed by using an anodic material having a large work function and capable of forming an anode. Note that the anodic materials shown as materials for forming the first electrode <b>102</b> can be used as the anodic material. Further, it is necessary to form the second electrode <b>103</b> by using a light transmitting anodic material in the case where the second electrode <b>103</b> functions as an electrode for emitting light that is generated in the first organic compound layer <b>105</b> or the second organic compound layer <b>106</b> to the outside. Furthermore, the second electrode <b>103</b> is formed by using a light blocking anodic material if a structure is formed in which light is emitted only from the first electrode <b>102</b> side.
0119<figref idref="DRAWINGS">FIG. 1A</figref> explains a case in which a positive polarity voltage is applied to the first electrode <b>102</b> and a negative polarity voltage is applied to the second electrode <b>103</b> in the light emitting element having the above structure. Note that, as explained above, the fixed reference voltage is applied to the opposing electrode <b>104</b>. The application of a positive polarity voltage is shown as a higher voltage than the reference voltage being applied. The application of a negative polarity voltage is shown as a lower voltage than the reference voltage being applied.
0120The first electrode <b>102</b> and the second electrode <b>103</b> are formed by using anodic materials here, and therefore electric current flows within the first organic compound layer <b>105</b> only from the first electrode <b>102</b>, to which a positive polarity voltage is applied. Carriers (electrons and holes) are injected within the first organic compound layer <b>105</b> by the electric current flowing within the first organic compound layer <b>105</b>, and therefore light emission occurs within the first organic compound layer <b>105</b> due to carrier recombination. If a forward bias is thus applied to the light emitting element, and carrier recombination develops within an inner portion of the organic compound layer, then the light emitting element emits light.
0121Regardless of being formed by using an anodic material, a negative polarity voltage is applied to the second electrode <b>103</b> at this point. Electric current therefore does not flow within the second organic compound layer <b>106</b> from the second electrode <b>103</b>, and then, the second organic compound layer <b>106</b> does not emit light. A negative polarity voltage is applied to the second electrode <b>103</b> here, and a reverse bias is therefore applied to the second organic compound layer <b>106</b>. Accumulation of electric charge in an inner portion of the second organic compound layer <b>106</b> can thus be relieved by application of the reverse bias.
0122In contrast to this, <figref idref="DRAWINGS">FIG. 1B</figref> is shows a case in which voltages having polarities that are the inverse of those shown in <figref idref="DRAWINGS">FIG. 1A</figref> are applied to the first electrode <b>102</b> and the second electrode <b>103</b>, respectively. That is, a negative polarity voltage, which is the inverse polarity with respect to the positive polarity of <figref idref="DRAWINGS">FIG. 1A</figref>, is applied to the first electrode <b>102</b>, and a positive polarity voltage, which is the inverse polarity with respect to the negative polarity of <figref idref="DRAWINGS">FIG. 1A</figref>, is applied to the second electrode <b>103</b>.
0123Electric current flows within the second organic compound layer <b>106</b> only from the second electrode <b>103</b> in this case. Carriers (electrons and holes) are injected within the second organic compound layer <b>106</b> by the electric current flowing within the second organic compound layer <b>106</b>, and therefore light emission occurs within the second organic compound layer <b>106</b> due to carrier recombination.
0124Regardless of being formed by using an anodic material, a negative polarity voltage is applied to the first electrode <b>102</b> at this point. Electric current therefore does not flow within the first organic compound layer <b>105</b> from the first electrode <b>102</b>, and then, the first organic compound layer <b>105</b> does not emit light. A negative polarity voltage is applied to the first electrode <b>102</b> here, and a reverse bias is therefore applied to the first organic compound layer <b>105</b>. Accumulation of electric charge in an inner portion of the first organic compound layer <b>105</b>, which shows light emission in <figref idref="DRAWINGS">FIG. 1A</figref>, can thus be relieved in <figref idref="DRAWINGS">FIG. 1B</figref> by application of the reverse bias.
0125Note that a case in which the first electrode <b>102</b> and the second electrode <b>103</b> are formed by using anodic materials, and the opposing electrode <b>104</b> is formed by using a cathodic material, is explained above. However, the present invention is not limited to such, and the first electrode <b>102</b> and the second electrode <b>103</b> can also be formed by using a cathodic material, and the opposing electrode <b>104</b> can be formed by using anodic materials.
EMBODIMENTS
0126Embodiments of the present invention are explained below.
Embodiment 1
0127A case of a structure in which a first electrode <b>302</b> and a second electrode <b>303</b> are formed by using anodic materials, an opposing electrode <b>304</b> is formed by using a cathodic material, and light that is generated in a first organic compound layer <b>305</b> and a second organic compound layer <b>306</b> is emitted from the first electrode <b>302</b> side (bottom emission type) is explained.
0128As shown in <figref idref="DRAWINGS">FIG. 3A</figref>, the first electrode <b>302</b> is electrically connected to a first electric power source <b>309</b>, and the second electrode <b>303</b> is electrically connected to a second electric power source <b>310</b>. In addition, the opposing electrode <b>304</b> is electrically connected to a third electric power source <b>311</b>. Note that the third electric power source <b>311</b> is controlled so as to always apply a constant fixed voltage (reference voltage). Note also that, in this embodiment, the voltage applied from the third electric power source <b>311</b> is set to 0 V.
0129Further, the first electric power source <b>309</b> and the second electric power source <b>310</b> are set so that reverse polarity voltages like those shown in <figref idref="DRAWINGS">FIG. 2</figref> are applied alternately to the electrodes (the first electrode <b>302</b> or the second electrode <b>303</b>) which the electric power sources are connected to, respectively. In this embodiment, +5 V is applied as a positive polarity voltage, and −5 V is applied as a negative polarity voltage, to each of the electrodes.
0130That is, when the +5 V voltage is applied from the first electric power source <b>309</b> to the first electrode <b>302</b>, the opposing electrode <b>304</b> is 0 V, and therefore a forward bias is applied to the first organic compound layer <b>305</b>, and then, a first light emitting element <b>307</b> emits light.
0131The −5 V voltage is applied simultaneously to the second electrode <b>303</b> from the second electric power source <b>310</b> at this point, and the opposing electrode <b>304</b> is 0 V, and therefore a reverse bias is applied to the second organic compound layer <b>306</b>, and then, a second light emitting element <b>308</b> does not emit light.
0132Conversely, when the −5 V voltage is applied from the first electric power source <b>309</b> to the first electrode <b>302</b>, the opposing electrode <b>304</b> is 0 V, and therefore a reverse bias is applied to the first organic compound layer <b>305</b>, and then, the first light emitting element <b>307</b> does not emit light.
0133The +5 V voltage is applied simultaneously to the second electrode <b>303</b> from the second electric power source <b>310</b> at this point, and the opposing electrode <b>304</b> is 0 V, and therefore a forward bias is applied to the second organic compound layer <b>306</b>, and then, the second light emitting element <b>308</b> emits light.
0134The structure of the light emitting elements formed on a substrate <b>301</b> is explained in detail next in this embodiment.
0135First, the first electrode <b>302</b> that serves as an anode of the first light emitting element <b>307</b> is formed. Note that the first electrode <b>302</b> is an anode, and further, it is necessary to provide the first electrode <b>302</b> with function for transmitting light that is generated in the organic compound layer, and therefore, the first electrode <b>302</b> is formed by sputtering using ITO, which is a light transmitting conductive film, at a film thickness of 100 nm.
0136The first organic compound layer <b>305</b> is formed next. Note that a laminate is formed in this embodiment by evaporating 40 nm of the hole transporting material α-NMD, 10 nm of the blocking material BCP, and 40 nm of the electron transporting material Alq<sub>3</sub>.
0137The opposing electrode <b>304</b> is formed next as a cathode. A laminate is formed in this embodiment from 2 nm of cesium fluoride (CsF) containing cesium (Cs), which has a small work function, 50 nm of ITO, which is a light transmitting conductive film, and in addition, 2 nm of CsF The opposing electrode <b>304</b> is formed in this embodiment by forming a laminate structure in which a material having a small work function is used in portions that are brought into contact with the organic compound layers, and a conductive material having superior light transmitting characteristics is sandwiched therebetween. The opposing electrode <b>304</b>, which possesses a plurality of functions, can thus be formed.
0138Note that a cathodic material is used as the material for forming the opposing electrode <b>304</b>. It is not always necessary to form a laminate structure like that explained above, however, and a single layer structure may also be formed, provided that a conductive material having light transmitting characteristics is employed.
0139Further, barium fluoride (BaF<sub>2</sub>), calcium fluoride (CaF), and the like can also be used as a substitute for cesium fluoride (CsF) when manufacturing the cathode.
0140The second organic compound layer <b>306</b> is formed next. Note that the second organic compound layer <b>306</b> is formed by evaporation using the same material as that used for the first organic compound layer <b>305</b> in this embodiment. However, the lamination order from the opposing electrode <b>304</b> side is the exact opposite to that of the first organic compound layer <b>305</b>, which is laminated on the first electrode <b>302</b>, because the relationship with the electrode is different. That is, the second organic compound layer <b>306</b> is formed of a laminate obtained by evaporating 40 nm of the electron transporting material Alq<sub>3</sub>, 10 nm of the blocking material BCP, and 40 nm of the hole transporting material α-NPD.
0141Lastly, the second electrode <b>303</b> is formed. The second electrode <b>303</b> is an anode of the second light emitting element <b>308</b>, and further, it is necessary to provide the second electrode <b>303</b> with function for blocking or reflecting light that develops in the organic compound layers. The second electrode <b>303</b> is therefore formed by using the anodic material gold (Au) at a film thickness of 100 nm, thus giving it light blocking characteristics.
0142Note that the second electrode <b>303</b> is formed on the second organic compound layer <b>306</b> that is already formed, and therefore the second electrode <b>303</b> is formed by using evaporation in order to minimize damage to the organic compound layer as much as possible during film formation. Note also that, even if elements residing in groups 4 to 11 of the long-period type period table, such as platinum (Pt), nickel (Ni), tungsten (W), chromium (Cr), molybdenum (Mo), iron (First electrode), cobalt (Co), copper (Cu), palladium (Pd) and the like, or chemical compounds of these elements, can be used as the anodic material employed in the second electrode <b>303</b> in this embodiment as a substitute for gold (Au) to form the second electrode <b>303</b> at a film thickness that possesses light blocking characteristics.
0143Note that, in the present invention, the first light emitting element <b>307</b> and the second light emitting element <b>308</b> are each structured by sharing the opposing electrode <b>304</b>, which is a cathode.
0144Light emitting elements capable of emitting light, which is generated in the organic compound layers (the first organic compound layer <b>305</b> and the second organic compound layer <b>306</b>), with efficiency only from the first electrode <b>302</b> side can thus be formed in this embodiment. Further, in the case where inverse polarity voltages are applied alternately, the first light emitting element <b>307</b> or the second light emitting element <b>308</b> can be made to emit light alternately, and simultaneously, electric charge accumulation that develops in an inner portion of the organic compound layer during light emission can be relieved by applying the reveres bias in the light emitting element to which a reverse bias is applied, and which does not emit light.
0145In this embodiment, differently from Embodiment 1, a case of a structure in which a second electrode <b>403</b> is formed by using light transmitting materials as shown in <figref idref="DRAWINGS">FIG. 4A</figref>, and light that is generated in a first organic compound layer <b>405</b> and a second organic compound layer <b>406</b> is emitted from the second electrode <b>403</b> side (top emission type) is explained.
0146As shown in <figref idref="DRAWINGS">FIG. 4A</figref>, the first electrode <b>402</b> is electrically connected to a first electric power source <b>409</b>, and the second electrode <b>403</b> is electrically connected to a second electric power source <b>410</b>. In addition, the opposing electrode <b>404</b> is electrically connected to a third electric power source <b>411</b>. Note that the third electric power source <b>411</b> is controlled so as to always apply a constant fixed voltage (reference voltage). Note also that, in this embodiment, the voltage applied from the third electric power source <b>411</b> is set to 0 V.
0147Further, the first electric power source <b>409</b> and the second electric power source <b>410</b> are set so that reverse polarity voltages like those shown by <figref idref="DRAWINGS">FIG. 2</figref> are applied alternately to the electrodes (the first electrode <b>402</b> or the second electrode <b>403</b>) which the electric power sources are connected to, respectively. In this embodiment, +5 V is applied as a positive polarity voltage, and −5 V is applied as a negative polarity voltage, to each of the electrodes.
0148The structure of the light emitting elements formed on a substrate <b>401</b> is explained in detail next in this embodiment.
0149First, the first electrode <b>402</b> that serves as an anode of the first light emitting element <b>407</b> is formed. Note that the first electrode <b>402</b> is an anode of the first light emitting element <b>407</b>, and further, in this embodiment, it is necessary to provide the first light emitting element <b>407</b> with function for blocking or reflecting light that is generated in the organic compound layer, and therefore, the first electrode <b>402</b> is formed by using gold (Au), which is an anodic material, at a film thickness of 100 nm.
0150Note that the first electrode <b>402</b> is formed by using evaporation. Note also that elements residing in groups 4 to 11 of the long-period type period table, such as platinum (Pt), nickel (Ni), tungsten (W), chromium (Cr), molybdenum (Mo), iron (Fe), cobalt (Co), copper (Cu), palladium (Pd) and the like, and chemical compounds of these elements, can be used as the anodic material employed in the first electrode <b>402</b> in this embodiment as a substitute for gold (Au) to form the first electrode <b>401</b> at a film thickness of an order so as to possesses light blocking characteristic.
0151The first organic compound layer <b>405</b> is formed next. Note that a laminate is formed in this embodiment by evaporating 30 nm of the hole injecting layer Cu-Pc, 40 nm of the hole transporting material α-NMD, 10 nm of the blocking material BCP, and 40 nm of the electron transporting material Alq<sub>3</sub>.
0152The opposing electrode <b>404</b> is formed next as a cathode. A laminate is formed in this embodiment from 2 nm of cesium fluoride (CsF) containing cesium (Cs), which has a small work function, 50 nm of ITO, which is a light transmitting conductive film, and in addition, 2 nm of CsF. The opposing electrode <b>404</b> is formed in this embodiment by forming a laminate structure in which a material having a small work function is used in portions that contact the organic compound layers, and a conductive material having superior light transmitting characteristics is sandwiched therebetween. The opposing electrode <b>404</b>, which possesses a plurality of functions, can thus be formed.
0153Note that a cathodic material is used as the material for forming the opposing electrode <b>404</b>. It is not always necessary to form a laminate structure like that explained above, however, and a single layer structure may also be formed, provided that a conductive material having light transmitting characteristics is employed.
0154Further, barium fluoride (BaF<sub>2</sub>), calcium fluoride (CaF), and the like can also be used as a substitute for cesium fluoride (CsF) when manufacturing the cathode.
0155The second organic compound layer <b>406</b> is formed next. Note that the second organic compound layer <b>406</b> is formed by evaporation using the same material as that used for the first organic compound layer <b>405</b> in this embodiment. However, the lamination order from the opposing electrode <b>404</b> side is the exact opposite to that of the first organic compound layer <b>405</b>, which is laminated on the first electrode <b>402</b>, because the lamination order depends on the relationship with the electrode. That is, the second organic compound layer <b>406</b> is formed by evaporating 40 nm of the electron transporting material Alq<sub>3</sub>, 10 nm of the blocking material BCP, 40 nm of the hole transporting material α-NPD and 30 nm of the hole injecting layer Cu-Pc.
0156The second electrode <b>403</b> is formed lastly. Note that the second electrode <b>403</b> is an anode in this embodiment, and further, it is necessary to provide the second electrode <b>403</b> with function for transmitting light that develops in the organic compound layers (the first organic compound layer <b>405</b> and the second organic compound layer <b>406</b>). The second electrode <b>403</b> is therefore formed by sputtering to a film thickness of 100 nm by using the light transmitting conductive ITO film. Note that the second electrode <b>403</b> is formed by sputtering after forming the second organic compound layer <b>406</b> in this embodiment. However, damage imparted during film formation by sputtering can be prevented because, unlike Embodiment 1, the film formation surface on which the second electrode <b>403</b> is formed is made of Cu-Pc.
0157Note that the first light emitting element <b>407</b> and the second light emitting element <b>408</b> are each structured by sharing the opposing electrode <b>404</b>, which is a cathode.
0158Light emitting elements capable of emitting light, which develops in the organic compound layers (the first organic compound layer <b>405</b> and the second organic compound layer <b>406</b>), with good efficiency only from the second electrode <b>403</b> side can thus be formed in this embodiment. Note that, in the case where the top emission light emitting element disclosed in this embodiment is used in an active matrix light emitting device in which a plurality of TFTs are formed, an aperture ratio reduction due to the TFTs does not cause a problem, and therefore it becomes possible to manufacture a light emitting device having a high aperture ration. Further, in the case where inverse polarity voltages are applied alternately, the first light emitting element <b>407</b> or the second light emitting element <b>408</b> can be made to emit light alternately, and charge accumulation that develops in an inner portion of the organic compound layer during light emission can also be relieved at the same time in the light emitting element to which a reverse bias is applied, and which does not emit light.
Embodiment 3
0159A passive (simple matrix) light emitting device having a light emitting element of the present invention is explained in this embodiment.
0160The structure of a passive light emitting device is shown in <figref idref="DRAWINGS">FIG. 5A</figref>. Reference numeral <b>507</b> denotes a pixel portion, which has a plurality of pixels <b>508</b>. Each of the pixels has one of a plurality of data lines <b>504</b>, one of a plurality of scanning lines (A) <b>505</b>, and one of a plurality of scanning lines (B) <b>506</b>. A first organic compound layer is formed between the data lines <b>504</b> and the scanning lines (A) <b>505</b>, and a second organic compound layer is formed between the data lines <b>504</b> and the scanning lines (B) <b>506</b>. The data lines <b>504</b> and the scanning lines (A) <b>505</b>, and the data lines <b>504</b> and the scanning lines (B) <b>506</b> become electrodes, forming first light emitting elements <b>509</b> and second light emitting elements <b>510</b>. Note that the pixels <b>508</b> have one each of the first light emitting elements <b>509</b> and the second light emitting elements <b>510</b> connected to the same data line <b>504</b> in this embodiment.
0161Signals input to the data lines <b>504</b> are controlled by a data line driver circuit <b>501</b>, signals input to the scanning lines (A) <b>505</b> are controlled by a scanning line driver circuit (A) <b>502</b>, and signals input to the scanning lines (B) are controlled by a scanning line driver circuit (B) <b>503</b>.
0162The voltage levels of signals input to the data lines <b>504</b>, the scanning lines (A) <b>505</b>, and the scanning lines (B) <b>506</b> when driving the light emitting elements of the present invention are shown in <figref idref="DRAWINGS">FIG. 5B</figref>. The voltage of each of the data lines <b>504</b> is constant (reference voltage). Voltages having positive polarity or negative polarity with respect to the reference voltage are input alternately to the scanning lines (A) <b>505</b> for fixed periods of time, and voltages having polarities that are the inverse of those input to the scanning lines (A) <b>505</b> are input alternately for the fixed periods of time to the scanning lines (B) <b>506</b>.
0163Forward biases and reverse biases are thus applied alternately to the first organic compound layer that structures the first light emitting element <b>509</b> and to the second organic compound layer that structures the second light emitting element <b>510</b>. This becomes a structure wherein a forward bias is applied to one light emitting element, either the first light emitting element <b>509</b> or the second light emitting element <b>510</b> formed in the pixel, while a reverse bias is applied to the other light emitting element. The accumulation of electric charge in inner portions of the organic compound layers of the light emitting elements, to which the forward bias is applied to cause light emission, can therefore be relieved by applying the reverse bias.
0164The first light emitting element <b>509</b> and the second light emitting element <b>510</b> can thus be made to alternately emit light by applying the forward bias alternately from the scanning line (A) <b>505</b> and the scanning line (B) <b>506</b>. Further, the accumulations of electric current that develop in the inner portions of the organic compound layers of the first light emitting element <b>509</b> and the second light emitting element <b>510</b> during light emission can be relieved alternately by applying the reverse bias alternately.
0165Note that this embodiment can be implement in free combination with Embodiments 1 or 2.
Embodiment 4
0166An example of using the present invention in an active matrix light emitting device that has four thin film transistors (TFT) in each pixel is explained in this embodiment.
0167A circuit diagram of a pixel in a light emitting device having a light emitting element of the present invention is shown in <figref idref="DRAWINGS">FIG. 6</figref>. Each pixel has a source signal line Si (where i is any one of 1 to x), a current supply line (A) Vi (where i is any one of 1 to x), an current supply line (B) V′i (where i is any one of 1 to x), and a gate signal line Gj (where j is any one of 1 to y).
0168Further, each pixel has a switching TFT (A) <b>601</b>, a switching TFT (B) <b>602</b>, a current control TFT (A) <b>603</b>, a current control TFT (B) <b>604</b>, a first light emitting element <b>605</b>, a second light emitting element <b>606</b>, a capacitor (A) <b>607</b>, and a capacitor (B) <b>608</b>.
0169Gate electrodes of the switching TFT (A) <b>601</b> and the switching TFT (B) <b>602</b> are both connected to the gate signal lines Gj. Further, regions of one type, either source regions or drain regions, of the switching TFT (A) <b>601</b> and the switching TFT (B) <b>602</b> are connected to the source signal line Si, and regions of the other type are connected to a gate electrode of the current control TFT (A) <b>603</b> for the case of the switching TFT (A) <b>601</b>, and to a gate electrode of the current control TFT (B) <b>604</b> for the case of the switching TFT (B) <b>602</b>, respectively.
0170A source region of the current control TFT (A) <b>603</b> is connected to the current supply line (A) Vi, and a drain region of the current control TFT (A) <b>603</b> is connected to one of two electrodes of the first light emitting element <b>605</b>. Of the two electrodes of the first light emitting element <b>605</b>, the one not connected to the drain region of the current control TFT (A) <b>603</b> is connected to an opposing electric power source <b>609</b>.
0171Note that, of the two electrodes of the first light emitting element <b>605</b>, the electrode that is connected to the drain region of the current control TFT (A) <b>603</b> is a first electrode <b>610</b>, and the electrode that is connected to the opposing electric power source <b>609</b> is an opposing electrode <b>611</b>.
0172A source region of the current control TFT (B) <b>604</b> is connected to the current supply line (B) V′i, and a drain region of the current control TFT (B) <b>604</b> is connected to one of two electrodes of the second light emitting element <b>606</b>. Of the two electrodes of the second light emitting element <b>606</b>, the one not connected to the drain region of the current control TFT (B) <b>604</b> is connected to the opposing electric power source <b>609</b>.
0173Note that, of the two electrodes of the second light emitting element <b>606</b>, the electrode that is connected to the drain region of the current control TFT (B) <b>604</b> is referred to as a second electrode <b>612</b>, and the electrode that is connected to the opposing electric power source <b>609</b> is referred to as the opposing electrode <b>611</b>. That is, the first light emitting element <b>605</b> and the second light emitting element <b>606</b> use the opposing electrode <b>611</b> as a shared electrode.
0174Further, the capacitor (A) <b>607</b> is formed between the gate electrode of the current control TFT (A) <b>603</b> and the current supply line (A) Vi, and the capacitor (B) <b>608</b> is formed between the gate electrode of the current control TFT (B) <b>604</b> and the current supply line (B) V′i.
0175A pixel portion of a light emitting device having a plurality of the pixels of <figref idref="DRAWINGS">FIG. 6</figref> is shown in <figref idref="DRAWINGS">FIG. 7A</figref>. The pixel portion <b>613</b> has source signal lines S<sub>1 </sub>to Sx, current supply lines (A) V<sub>1 </sub>to Vx, current supply lines (B) V′<sub>1 </sub>to V′x, and gate signal lines G<sub>1 </sub>to Gy. A plurality of pixels <b>614</b> are formed in a matrix shape in the pixel potion <b>613</b>.
0176Operations of the TFTs in each pixel, and the voltage levels of signals input to the current supply line (A) Vi, the current supply line (B) V′i, and the opposing electrode <b>611</b> when driving the first light emitting element <b>605</b> and the second light emitting element <b>606</b> are shown in <figref idref="DRAWINGS">FIG. 7B</figref>. Note that a constant voltage (reference voltage) is always applied to the opposing electrode <b>611</b>, and positive polarity voltages, which are high voltages with respect to the reference voltage, or negative polarity voltages, which are low voltages with respect to the reference voltage, are input to the current supply line (A) and the current supply line (B). Note also that the positive polarity voltages and the negative polarity voltages are controlled so as to be applied alternately for fixed periods of time. Further, the voltages applied to the current supply line (A) and the current supply line (B) have inverse polarities at the same timing.
0177If the switching TFT (A) <b>601</b> and the switching TFT (B) <b>602</b> of the pixel are simultaneously in an on state, and the current control TFT (A) <b>603</b> and the current control TFT (B) <b>604</b> are in an on state, then the voltage input to the current supply line (A) is applied to the first electrode <b>610</b> of the first light emitting element <b>605</b>, and the voltage input to the current supply line (B) is applied to the second electrode <b>612</b> of the second light emitting element <b>606</b>.
0178In the case where the first electrode <b>610</b> and the second electrode <b>612</b> are formed by using anodic materials, and the opposing electrode <b>611</b> is formed by using a cathodic material, a forward bias is applied to the light emitting element that has an electrode to which the positive polarity voltage is applied (the first electrode <b>610</b> or the second electrode <b>612</b>), and therefore this light emitting element emits light. A reverse bias is applied to the light emitting element that has an electrode to which the negative polarity voltage is applied (the first electrode <b>610</b> or the second electrode <b>612</b>), and therefore this light emitting element does not emit light.
0179Conversely, in the case where the first electrode <b>610</b> and the second electrode <b>612</b> are formed by using a cathodic material, and the opposing electrode <b>611</b> is formed by using an anodic material, a forward bias is applied to the light emitting element that has an electrode to which the negative polarity voltage is applied (the first electrode <b>610</b> or the second electrode <b>612</b>), and therefore this light emitting element emits light. A reverse bias is applied to the light emitting element that has an electrode to which the positive polarity voltage is applied (the first electrode <b>610</b> or the second electrode <b>612</b>), and therefore this light emitting element does not emit light.
0180The voltage applied to the opposing electrode <b>611</b> is set to 0 V in this embodiment, and the voltages applied to the first electrode and the second electrode from the current supply line (A) Vi and the current supply line (B) V′i are set to −5 V (the negative polarity voltage) and +5 V (the positive polarity voltage), respectively.
0181The forward bias and the reverse bias can thus be applied alternately from the electric current supply line (A) Vi and the electric current supply line (B) V′i. Note that the first light emitting element <b>605</b> and the second light emitting element <b>606</b> formed in the same pixel are structured so that when the forward bias is applied to one of the light emitting elements, the reverse bias is applied to the other light emitting element, and therefore, the light emitting elements to which the forward bias is applied are made to emit light alternately, and at the same time, the accumulation of electric charge in inner portions of the organic compound layers of the light emitting elements can be relieved by application of the reverse bias.
0182Note that this embodiment can be implemented by freely combining with the structure shown in Embodiments 1 or 2.
Embodiment 5
0183The structure of the active matrix light emitting device explained in Embodiment 4 is explained in Embodiment 5 using <figref idref="DRAWINGS">FIGS. 8A to 8D</figref>. Note that, of the TFTs structuring the pixel portion, only a current control TFT (A) <b>802</b> and a current control TFT (B) <b>803</b> are explained.
0184The current control TFT (A) <b>802</b> and the current control TFT (B) <b>803</b> are formed on a substrate <b>801</b> in <figref idref="DRAWINGS">FIG. 8A</figref>. Note that the current control TFT (A) <b>802</b> has an active layer that contains a source region <b>804</b>, a drain region <b>805</b>, and a channel region <b>806</b>, and a gate electrode <b>807</b> that is disposed overlapping with the channel region <b>806</b> through a gate insulating film <b>812</b>. Further, the source region <b>804</b> is electrically connected to a source side driver circuit (not shown) by a wiring (a) <b>814</b>, and the drain region <b>805</b> is electrically connected to a first electrode <b>816</b> formed by the wiring (a) <b>814</b> through an interlayer insulating film <b>813</b>.
0185The current control TFT (B) <b>803</b> also has the same structure as the current control TFT (A) <b>802</b>, and has an active layer that contains a source region <b>808</b>, a drain region <b>809</b>, and a channel region <b>810</b> and a gate electrode <b>811</b>. However, the source region <b>808</b> is electrically connected to a source side driver circuit (not shown) by a wiring (b) <b>815</b>.
0186Note that it is preferable to form the current control TFT (A) <b>802</b> and the current control TFT (B) <b>803</b> by using p-channel TFTs in this embodiment because the first electrode <b>816</b> is formed by using an anodic material. Further, it is preferable to form the current control TFT (A) <b>802</b> and the current control TFT (B) <b>803</b> by n-channel TFTs if the first electrode is formed by using a cathodic material.
0187Note that the materials shown in the embodiment mode of the present invention can be used as the anodic material that forms the first electrode <b>816</b> in this embodiment. The first electrode <b>816</b> is formed by using ITO as the anodic material in this embodiment. Note that the first electrode <b>816</b> formed here is formed by sputtering ITO to have a thickness of 100 nm.
0188A first insulating film <b>817</b> made from an organic resin material is formed next on the wiring (a) <b>814</b>, the wiring (b) <b>815</b>, and the first electrode <b>816</b> as shown in <figref idref="DRAWINGS">FIG. 8B</figref>. The first insulating film <b>817</b> is formed by using a photosensitive resin material in this embodiment. Note that negative type or positive type materials can be used as the photosensitive resin material. The first insulating film <b>817</b> is formed to have a thickness of 1 to 2 μm by using a positive type photosensitive polyimide or photosensitive acrylic in this embodiment.
0189In addition, a second insulating film <b>818</b> made from an inorganic material is formed on the first insulating film <b>817</b> in this embodiment. Specifically, the second insulating film <b>818</b> is formed by using a silicon nitride film that is formed by sputtering. Note that the second insulating film <b>818</b> is patterned so that it is not formed on the first electrode <b>816</b> or the wiring (b) <b>815</b> except for a portion, as shown in <figref idref="DRAWINGS">FIG. 8B</figref>. Deterioration of the material used for forming the organic compound layers due to oxygen, moisture, and the like that is generated from the organic resin material used in forming the first insulating film <b>817</b> can be prevented by forming the second insulating film <b>818</b> using the silicon nitride film here.
0190An auxiliary wiring <b>819</b> is formed next contacting the wiring (b) <b>815</b>. Note that the auxiliary wiring formed hear is formed in order to electrically connect the drain region <b>809</b> of the current control TFT (B) and a second electrode that is formed later.
0191A first organic compound layer <b>820</b> is formed next on the first electrode <b>816</b>. The materials shown in the embodiment mode of the present invention can be used as the material that forms the first organic compound layer <b>820</b>, and a laminate is formed in this embodiment by evaporating 40 nm of the hole transporting material α-NPD, 10 nm of the blocking material BCP, and 40 nm of the electron transporting material Alq<sub>3</sub>.
0192An opposing electrode <b>821</b> is formed next on the first organic compound layer <b>820</b> so as to completely cover the first organic compound layer <b>820</b>. The opposing electrode <b>821</b> is formed by using a cathodic material in this embodiment, specifically, by a laminate of 2 nm of cesium fluoride (CsF) that contains cesium (Cs), which has a small work function, 50 nm of ITO, which is a light transmitting conductive film, and in addition, 2 nm of CsF.
0193A second organic compound layer <b>822</b> is formed next on the opposing electrode <b>821</b> so as to completely cover the opposing electrode <b>821</b>. Note that the same material as that used for the first organic compound layer <b>8920</b> is formed by evaporation in this embodiment. However, the lamination order from the opposing electrode <b>821</b> side is the exact opposite to that of the first organic compound layer <b>820</b>, which is laminated on the first electrode <b>816</b>, because the lamination order depends on the relationship with the electrode. That is, the laminate is formed by evaporating 40 nm of the electron transporting material Alq<sub>3</sub>, 10 nm of the blocking material BCP, and 40 nm of the hole transporting material α-NPD.
0194Lastly, a second electrode <b>823</b> is formed on the second organic compound layer <b>822</b>, completely covering the second organic compound layer <b>822</b>, and contacting the auxiliary wiring <b>819</b> formed above. Note that the second electrode <b>823</b> is formed by using an anodic material. The second electrode <b>823</b> is provided with light blocking characteristics in this embodiment for the formation by forming it using the anodic material gold (Au) to have a thickness of 100 nm.
0195An active matrix light emitting device that has a first light emitting element <b>824</b> including the first electrode <b>816</b>, the first organic compound layer <b>820</b>, and the opposing electrode <b>821</b>, and a second light emitting element <b>825</b> including the opposing electrode <b>821</b>, the second organic compound layer <b>822</b>, and the second electrode <b>823</b> can thus be produced. Note that the first light emitting element <b>824</b> and the second light emitting element <b>825</b> share the opposing electrode <b>821</b>, which is a cathode, in the present invention, thus structuring the elements.
0196As described above, in this embodiment, light emitting elements capable of emitting light that is generated in the organic compound layers (the first organic compound layer <b>820</b> and the second organic compound layer <b>822</b>) efficiently only from the first electrode <b>816</b> side can thus be formed. Note that the structure of the present invention is not limited by the structure shown in this embodiment. For example, the first electrode can also be formed by using an anodic material that has light blocking characteristics, and the second electrode <b>823</b> can also be formed by using a material that has light transmitting characteristics in the case where the first electrode <b>816</b> and the second electrode <b>823</b> are formed by anodic materials. Further, the first electrode <b>816</b> and the second electrode <b>823</b> can both be formed by using light transmitting anodic materials depending upon the circumstances.
Embodiment 6
0197A case of manufacturing a passive (simple matrix) light emitting device having the element structure of the present invention is explained in this embodiment. <figref idref="DRAWINGS">FIG. 9</figref> is used in the explanation. Reference numeral <b>901</b> denotes a glass substrate in <figref idref="DRAWINGS">FIG. 9</figref>, and reference numeral <b>902</b> denotes a first electrode that functions as an anode. Note that, after forming ITO by sputtering, the first electrode <b>902</b> is formed by patterning. Although not shown in <figref idref="DRAWINGS">FIG. 9</figref>, a plurality of first electrodes <b>902</b> are disposed in stripe shapes parallel to the page.
0198Further, banks <b>903</b> made from an insulating material are formed so as to intersect with the first electrodes <b>902</b> disposed in a stripe shape. The banks <b>903</b> are formed contacting the first electrode <b>902</b> in a direction orthogonal to the page.
0199First organic compound layers <b>904</b> are formed next. The first organic compound layers <b>904</b> are formed by laminating 40 nm of the hole transporting material α-NPD, 10 nm of the blocking material BCP, and 40 nm of the electron transporting material Alq<sub>3 </sub>by using evaporation in this embodiment. Further, the first organic compound layers <b>904</b> are formed along grooves formed by the banks <b>903</b>, and therefore, are disposed in a stripe shape in a direction orthogonal to the page.
0200Opposing electrodes <b>905</b> are formed next. The opposing electrodes <b>905</b> function as cathodes, and further, are formed by a light transmitting conductive material. The opposing electrodes <b>905</b> are formed by a laminate of 2 nm of cesium fluoride (CsF) containing cesium (Cs), which has a small work function, 50 nm of ITO, which is a light transmitting conductive film, and in addition, 2 nm of CsF. The opposing electrodes <b>905</b> can thus be formed to possess a plurality of functions by using a material having a small work function in portions that contact the organic compound layers, and further, by forming a laminate structure in which a conductive material having superior light transmitting characteristics is sandwiched therebetween.
0201Second organic compound layers <b>906</b> are formed next. Note that the second organic compound layers <b>906</b> are formed by evaporation using the same material as that used for the first organic compound layers <b>904</b> in this embodiment. However, the lamination order from the opposing electrode <b>905</b> side is the exact opposite to that of the first organic compound layers <b>904</b>, which are laminated on the first electrodes <b>902</b>, because the lamination order depends on the relationship with the electrodes. That is, the laminates are formed by evaporating 40 nm of the electron transporting material Alq<sub>3</sub>, 10 nm of the blocking material BCP, and 40 nm of the hole transporting material α-NPD.
0202Lastly, second electrodes <b>907</b> are formed. It is necessary to provide function as anodes and function for blocking or reflecting light that is generated in the organic compound layers to the second electrodes, and therefore, the second electrodes <b>907</b> are provided with light blocking characteristics and formed to have a thickness of 100 nm by using the anodic material gold (Au).
0203A passive matrix light emitting device having first light emitting elements <b>908</b> including the first electrodes <b>902</b>, the first organic compound layers <b>904</b>, and the opposing electrodes <b>905</b>, and second light emitting elements <b>909</b> including the opposing electrodes <b>905</b>, the second organic compound layers <b>906</b>, and the second electrodes <b>907</b> is thus formed.
0204Note that the first electrodes <b>902</b> are formed by using a light transmitting anodic material in the passive matrix light emitting device disclosed in this embodiment, and therefore, light that is generated in the first organic compound layers <b>904</b> or the second organic compound layers <b>906</b> is emitted to the lower side (the substrate <b>901</b> side).
0205A ceramic substrate is prepared next as a sealing substrate <b>911</b>. Light blocking characteristics are fine with the structure of this embodiment, and therefore, the ceramic substrate is used, but a substrate made from plastic, glass, or quartz can also be used.
0206The sealing substrate <b>911</b> thus prepared is bonded by using a sealant <b>912</b> made from an ultraviolet setting resin. Note that an inside <b>910</b> of the sealant <b>912</b> becomes a sealed space, and an inert gas such as nitrogen or argon can be filled into the space. Furthermore, it is effective to provide a hygroscopic material, typically barium oxide, within the sealed space <b>910</b>. Lastly, an FPC <b>913</b> is attached, thus completing the passive light emitting device. Note that the sealing structure shown in this embodiment can also be used for the active matrix light emitting devices shown in Embodiment 4 and Embodiment 5, not only for the passive matrix light emitting device shown in Embodiment 3.
Embodiment 7
0207The light-emitting device fabricated in accordance with the present invention is of the self-emission type, and thus exhibits more excellent recognizability of the displayed image in a light place as compared to the liquid crystal display device. Furthermore, the light-emitting device has a wider viewing angle. Accordingly, various electronic apparatuses can be completed by using the light-emitting device of the present invention to a display portion.
0208Such electronic apparatuses manufactured by the present invention include a video camera, a digital camera, a goggles-type display (head mount display), a navigation system, a sound reproduction device (a car audio equipment, an audio set and the like), a laptop personal computer, a game machine, a portable information terminal (a mobile computer, a cellular phone, a portable game machine, an electronic book, or the like), an image reproduction apparatus including a recording medium (more specifically, an apparatus which can reproduce a recording medium such as a digital versatile disc (DVD) and so forth, and includes a display for displaying the reproduced image), or the like. In particular, in the case of the portable information terminal, use of the light-emitting device with a light-emitting element is preferable, since the portable information terminal that is likely to be viewed from a tilted direction is often required to have a wide viewing angle. <figref idref="DRAWINGS">FIGS. 10A to 10H</figref> shows various specific examples of such electronic apparatus.
0209FIG, <b>10</b>A illustrates a display-device which includes a frame <b>2001</b>, a support table <b>2002</b>, a display portion <b>2003</b>, a speaker portion <b>2004</b>, a video input terminal <b>2005</b> or the like. The light-emitting device manufactured by the present invention can be used for the display portion <b>2003</b>. The light-emitting device is of the self-emission type and therefore requires no backlight. Thus, the display portion thereof can have a thickness thinner than that of the liquid crystal display device. The display device is including all of the display devices for displaying information, such as a personal computer, a receiver of TV broadcasting and an advertising display.
0210<figref idref="DRAWINGS">FIG. 10B</figref> illustrates a digital still camera which includes a main body <b>2101</b>, a display portion <b>2102</b>, an image receiving portion <b>2103</b>, an operation key <b>2104</b>, an external connection port <b>2105</b>, a shutter <b>2106</b>, or the like. The light-emitting device manufactured by the present invention can be used for the display portion <b>2102</b>.
0211<figref idref="DRAWINGS">FIG. 10C</figref> illustrates a laptop type (notebook type) personal computer which includes a main body <b>2201</b>, a casing <b>2202</b>, a display portion <b>2203</b>, a keyboard <b>2204</b>, an external connection port <b>2205</b>, a pointing mouse <b>2206</b>, or the like. The light-emitting device manufactured by the present invention can be used to the display portion <b>2203</b>.
0212<figref idref="DRAWINGS">FIG. 10D</figref> illustrates a mobile computer which includes a main body <b>2301</b>, a display portion <b>2302</b>, a switch <b>2303</b>, an operation key <b>2304</b>, an infrared port <b>2305</b>, or the like. The light-emitting device manufactured by the present invention can be used to the display portion <b>2302</b>.
0213<figref idref="DRAWINGS">FIG. 10E</figref> illustrates an image reproduction apparatus including a recording medium (more specifically, a DVD reproduction apparatus), which includes a main body <b>2401</b>, a casing <b>2402</b>, a display portion A <b>2403</b>, another display portion B <b>2404</b>, a recording medium (DVD or the like) reading portion <b>2405</b>, an operation key <b>2406</b>, a speaker portion <b>2407</b> or the like. The display portion A <b>2403</b> is used mainly for displaying image information, while the display portion B <b>2404</b> is used mainly for displaying character information. The light-emitting device manufactured by the present invention can be used to the display potion A <b>2403</b> and the display portion B <b>2404</b>. Note that the image reproduction apparatus including a recording medium further includes a domestic game machine or the like.
0214<figref idref="DRAWINGS">FIG. 10F</figref> illustrates a goggle type display (head mounted display) which includes a main body <b>2501</b>, a display portion <b>2502</b>, an arm portion <b>2503</b>. The light-emitting device manufactured by the present invention can be used to the display portion <b>2502</b>.
0215<figref idref="DRAWINGS">FIG. 10G</figref> illustrates a video camera which includes a main body <b>2601</b>, a display portion <b>2602</b>, an casing <b>2603</b>, an external connecting port <b>2604</b>, a remote control receiving portion <b>2605</b>, an image receiving portion <b>2606</b>, a battery <b>2607</b>, a sound input portion <b>2608</b>, an operation key <b>2609</b>, an eyepiece potion <b>2610</b> or the like. The light-emitting device manufactured by the present invention can be used to the display portion <b>2602</b>.
0216<figref idref="DRAWINGS">FIG. 10H</figref> illustrates a cellular phone which includes a main body <b>2701</b>, a casing <b>2702</b>, a display portion <b>2703</b>, a sound input portion <b>2704</b>, a sound output portion <b>2705</b>, an operation key <b>2706</b>, an external connecting port <b>2707</b>, an antenna <b>2708</b>, or the like. The light-emitting device manufactured by the present invention can be used to the display portion <b>2703</b>. Note that the display portion <b>2703</b> can reduce power consumption of the cellular phone by displaying white-colored characters on a black-colored background.
0217When the brighter luminance of the organic material becomes available in the future, the light-emitting device manufactured by the present invention will be applicable to a front-type or rear-type projector in which light including output image information is enlarged by means of lenses or the like to be projected.
0218The aforementioned electronic apparatuses are more likely to be used for display information distributed through a telecommunication path such as Internet, a CATV (cable television system), and in particular likely to display moving image information. The light-emitting device is suitable for displaying moving images since the organic material can exhibit a high response speed.
0219A portion of the light-emitting device that is emitting light consumes power, so it is desirable to display information in such a manner that the light-emitting portion therein becomes as small as possible. Accordingly, when the light-emitting device is applied to a display portion which mainly displays character information, e.g., a display portion of a portable information terminal, and more particular, a cellular phone or a sound reproduction device, it is desirable to drive the light-emitting device so that the character information is formed by a light-emitting portion while a non-emission portion corresponds to the background.
0220As set forth above, the light-emitting device formed by using the present invention can be applied variously to a wide range of electronic apparatuses in all fields. The electronic apparatuses in this embodiment can be completed by using a light-emitting device shown in Embodiments 1 through 6 to the display portion.
0221By implementing the present invention, voltages having different polarities can be applied alternately for fixed periods of time to a first light emitting element and a second light emitting element, and therefore, light can be emitted alternately from one of the first light emitting element and the second light emitting element, to which a forward bias is applied. Further, while one of the light emitting elements is emitting light, a reverse bias is applied to the other light emitting element, and therefore, the accumulation of electric charge in an inner portion of an organic compound layer forming the light emitting element can be relieved. Reductions in the light emitting lifetime and degradation in brightness can thus be suppressed. In addition, even if voltages having different polarities are applied alternately to the light emitting elements of the present invention, the light emitting element to which a forward bias is applied will emit light, and therefore, it becomes possible to perform display without an effective shortening of the light emission time. Consequently, problems of the display becoming dark, and problems of organic compound layer deterioration that occurs by applying a high voltage so as to maintain a predetermined brightness can be solved.
Contents5
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| US8169137B2 | Cited by | United States of America | Applicant |
| US8883553B2 | Cited by | United States of America | Search report |
| US2007085070A1 | Cited by | United States of America | Pre-grant |
| US2010220041A1 | Cited by | United States of America | Pre-grant |
| WO02101838A1 | Cites | World Intellectual Property Organization (WIPO) | Applicant |
| EP0215683A2 | Cites | European Patent Office (EPO) | Applicant |
| EP0855848A2 | Cites | European Patent Office (EPO) | Applicant |
| EP0948063A2 | Cites | European Patent Office (EPO) | Applicant |
| EP1094436A2 | Cites | European Patent Office (EPO) | Applicant |
| JP2000195664A | Cites | Japan | Applicant |
| JP2000260572A | Cites | Japan | Applicant |
| US2001007447A1 | Cites | United States of America | Search report |
| US2001031509A1 | Cites | United States of America | Applicant |
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| JP2001222255A | Cites | Japan | Applicant |
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| US5552678A | Cites | United States of America | Applicant |
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| US5677546A | Cites | United States of America | Applicant |
| US5682043A | Cites | United States of America | Applicant |
| US5757139A | Cites | United States of America | Search report |
| US5837391A | Cites | United States of America | Applicant |
| US5917280A | Cites | United States of America | Search report |
| US5970318A | Cites | United States of America | Applicant |
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| US6297495B1 | Cites | United States of America | Applicant |
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| US6423429B2 | Cites | United States of America | Applicant |
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| US6844025B2 | Cites | United States of America | Applicant |
| US6876007B2 | Cites | United States of America | Applicant |
| JPH04192376A | Cites | Japan | Applicant |
| JPH06318725A | Cites | Japan | Applicant |
| JPH09199276A | Cites | Japan | Applicant |
3 members in 2 offices; this record represents the family
Priority claims2
| Document | Office | Kind | Date |
|---|---|---|---|
| 2002106787 | Japan | – | |
| 2002106787 | Japan | A |
Members3
| Document | Office | Kind | |
|---|---|---|---|
| JP2003303683A | Japan | A | |
| US2003218173A1 | United States of America | A1 | |
| US7535440B2This record | United States of America | B2 |
104 transactions on the USPTO file
Allowed after 4 non-final rejections, 3 final rejections, 3 RCEs and 1 appeal.
- Non-final rejections
- 4
- Final rejections
- 3
- RCEs
- 3
- Appeals
- 1
Over time
Point at a mark for the transactionTransactions
| Event | Code | |
|---|---|---|
| Expire PatentEXP. | EXP. | |
| Maintenance Fee Reminder MailedREM. | REM. | |
| Recordation of Patent Grant MailedPGM/ | PGM/ | |
| Patent Issue Date Used in PTA CalculationAllowedPTAC | PTAC | |
| Issue Notification MailedAllowedWPIR | WPIR | |
| Dispatch to FDCD1935 | D1935 | |
| Application Is Considered Ready for IssuePILS | PILS | |
| Issue Fee Payment VerifiedN084 | N084 | |
| Issue Fee Payment ReceivedIFEE | IFEE | |
| Mail Response to 312 Amendment (PTO-271)MN271 | MN271 | |
| Response to Amendment under Rule 312N271 | N271 | |
| Amendment after Notice of Allowance (Rule 312)AllowedA.NA | A.NA | |
| Mail Notice of AllowanceAllowedMN/=. | MN/=. | |
| Notice of Allowance Data Verification CompletedAllowedN/=. | N/=. | |
| Date Forwarded to ExaminerFWDX | FWDX | |
| Response after Non-Final ActionA... | A... | |
| Mail Non-Final RejectionNon-final rejectionMCTNF | MCTNF | |
| Non-Final RejectionNon-final rejectionCTNF | CTNF | |
| Date Forwarded to ExaminerFWDX | FWDX | |
| Response after Non-Final ActionA... | A... | |
| Mail Non-Final RejectionNon-final rejectionMCTNF | MCTNF | |
| Non-Final RejectionNon-final rejectionCTNF | CTNF | |
| Date Forwarded to ExaminerFWDX | FWDX | |
| Date Forwarded to ExaminerFWDX | FWDX | |
| Disposal for a RCE / CPA / R129AbandonedABN9 | ABN9 | |
| Request for Continued Examination (RCE)RCEX | RCEX | |
| Workflow - Request for RCE - BeginBRCE | BRCE | |
| Information Disclosure Statement consideredIDSC | IDSC | |
| Information Disclosure Statement (IDS) FiledM844 | M844 | |
| Information Disclosure Statement (IDS) FiledWIDS | WIDS | |
| Mail Final Rejection (PTOL - 326)Final rejectionMCTFR | MCTFR | |
| Final RejectionFinal rejectionCTFR | CTFR | |
| Date Forwarded to ExaminerFWDX | FWDX | |
| Information Disclosure Statement consideredIDSC | IDSC | |
| Reference capture on IDSRCAP | RCAP | |
| Information Disclosure Statement (IDS) FiledM844 | M844 | |
| Response after Non-Final ActionA... | A... | |
| Request for Extension of Time - GrantedXT/G | XT/G | |
| Information Disclosure Statement (IDS) FiledWIDS | WIDS | |
| Mail Non-Final RejectionNon-final rejectionMCTNF | MCTNF | |
| Non-Final RejectionNon-final rejectionCTNF | CTNF | |
| Date Forwarded to ExaminerFWDX | FWDX | |
| Date Forwarded to ExaminerFWDX | FWDX | |
| Disposal for a RCE / CPA / R129AbandonedABN9 | ABN9 | |
| Request for Continued Examination (RCE)RCEX | RCEX | |
| Workflow - Request for RCE - BeginBRCE | BRCE | |
| Notice of Appeal FiledN/AP | N/AP | |
| Request for Extension of Time - GrantedXT/G | XT/G | |
| Mail Advisory Action (PTOL - 303)MCTAV | MCTAV | |
| Advisory Action (PTOL-303)CTAV | CTAV | |
| Date Forwarded to ExaminerFWDX | FWDX | |
| Response after Final ActionA.NE | A.NE | |
| Mail Final Rejection (PTOL - 326)Final rejectionMCTFR | MCTFR | |
| Final RejectionFinal rejectionCTFR | CTFR | |
| Case Docketed to Examiner in GAUDOCK | DOCK | |
| Date Forwarded to ExaminerFWDX | FWDX | |
| Date Forwarded to ExaminerFWDX | FWDX | |
| Disposal for a RCE / CPA / R129AbandonedABN9 | ABN9 | |
| Request for Continued Examination (RCE)RCEX | RCEX | |
| Request for Extension of Time - GrantedXT/G | XT/G | |
| Workflow - Request for RCE - BeginBRCE | BRCE | |
| Mail Advisory Action (PTOL - 303)MCTAV | MCTAV | |
| Advisory Action (PTOL-303)CTAV | CTAV | |
| Date Forwarded to ExaminerFWDX | FWDX | |
| Response after Final ActionA.NE | A.NE | |
| Case Docketed to Examiner in GAUDOCK | DOCK | |
| Mail Final Rejection (PTOL - 326)Final rejectionMCTFR | MCTFR | |
| Final RejectionFinal rejectionCTFR | CTFR | |
| Date Forwarded to ExaminerFWDX | FWDX | |
| Information Disclosure Statement consideredIDSC | IDSC | |
| Reference capture on IDSRCAP | RCAP | |
| Information Disclosure Statement (IDS) FiledM844 | M844 | |
| Information Disclosure Statement (IDS) FiledWIDS | WIDS | |
| Response after Non-Final ActionA... | A... | |
| Mail Non-Final RejectionNon-final rejectionMCTNF | MCTNF | |
| Non-Final RejectionNon-final rejectionCTNF | CTNF | |
| Date Forwarded to ExaminerFWDX | FWDX | |
| Response to Election / Restriction FiledELC. | ELC. | |
| Reference capture on IDSRCAP | RCAP | |
| Information Disclosure Statement (IDS) FiledM844 | M844 | |
| Information Disclosure Statement (IDS) FiledWIDS | WIDS | |
| Mail Restriction RequirementMCTRS | MCTRS | |
| Restriction/Election RequirementCTRS | CTRS | |
| Case Docketed to Examiner in GAUDOCK | DOCK | |
| Case Docketed to Examiner in GAUDOCK | DOCK | |
| Miscellaneous Incoming LetterLET. | LET. | |
| Case Docketed to Examiner in GAUDOCK | DOCK | |
| IFW TSS Processing by Tech Center CompleteTSSCOMP | TSSCOMP | |
| Case Docketed to Examiner in GAUDOCK | DOCK | |
| Transfer Inquiry to GAUTI1050 | TI1050 | |
| Reference capture on IDSRCAP | RCAP | |
| Application Dispatched from OIPEOIPE | OIPE | |
| Application Is Now CompleteCOMP | COMP | |
| Payment of additional filing fee/PreexamFLFEE | FLFEE | |
| A statement by one or more inventors satisfying the requirement under 35 USC 115, Oath of the ApplicOATHDECL | OATHDECL | |
| Information Disclosure Statement (IDS) FiledM844 | M844 | |
| Information Disclosure Statement (IDS) FiledWIDS | WIDS | |
| Notice Mailed--Application Incomplete--Filing Date AssignedINCD | INCD | |
| IFW Scan & PACR Auto Security ReviewSCAN | SCAN | |
| IFW Scan & PACR Auto Security ReviewSCAN | SCAN |
9 legal events, as the office reported them to INPADOC
Over the term
Point at a mark for the eventEvents
| Event | Code | |
|---|---|---|
| Lapsed due to failure to pay maintenance feeLapsedFP | FP | |
| Lapse for failure to pay maintenance feesLapsedPATENT EXPIRED FOR FAILURE TO PAY MAINTENANCE FEES (ORIGINAL EVENT CODE: EXP.); ENTITY STATUS OF PATENT OWNER: LARGE ENTITYLAPS | LAPS | |
| Information on status: patent discontinuationPATENT EXPIRED DUE TO NONPAYMENT OF MAINTENANCE FEES UNDER 37 CFR 1.362STCH | STCH | |
| Fee payment procedureMAINTENANCE FEE REMINDER MAILED (ORIGINAL EVENT CODE: REM.); ENTITY STATUS OF PATENT OWNER: LARGE ENTITYFEPP | FEPP | |
| Fee paymentFPAY | FPAY | |
| Fee paymentFPAY | FPAY | |
| Information on status: patent grantGrantedPATENTED CASESTCF | STCF | |
| Fee payment procedurePAYOR NUMBER ASSIGNED (ORIGINAL EVENT CODE: ASPN); ENTITY STATUS OF PATENT OWNER: LARGE ENTITYFEPP | FEPP | |
| AssignmentAS | AS |
Numbers
- Publication
- 7535440
- Application
- 10406598
Titles
- English
- Light emitting device
Patent term adjustment
- A delay
- +334 daysthe office missed an examination deadline
- Applicant delay
- −143 days
- Net adjustment
- 191 days
Classification
- CPC, 7
- H10K59/32
- H10K59/173
- H10K59/122
- H10K59/12
- H10K2102/3026
- H10K71/841
- H10K59/17
- IPC, 4
- G09G3 30
- H05B33 20
- H05B33 26
- H10K59 12